1. Field of the invention
This invention relates to an afocal zoom lens, and more particularly to an afocal zoom lens suited for a microscope.
2. Related Background Art
As afocal zoom lenses used in microscopes or the like, lenses are conventionally known which are disclosed in, e.g., Japanese Patent Publications No. 6-48328 and No. 6-77104.
In recent years, in the field of microscopes, in particular, stereomicroscopes, target specimens to be observed have become rich in variety. Accordingly, it is sought to achieve a zoom ratio much higher than ever. None of conventional afocal zoom lenses, however, have any satisfactory zoom ratio and hence have a problem that any observation well satisfactory to user's demands can not be made.